The backlight module provides a light source for a display device such as a liquid crystal display (LCD). The LCD itself does not emit light, and the light guide plate (LGP) is an important part of the backlight module. The function of the light guide plate is to convert a line light source into a surface light source.
Referring to FIG. 1, a schematic cross section view of a light guide plate in a related art is shown. The light guide plate 10 includes: a light entrance surface 101 for receiving light emitted by the LED light source 20, a light exit surface 102 connected with the light entrance surface 101, and a bottom surface 103 connected with the light entrance surface 101 and opposite to the light exit surface 102. The bottom surface 103 is provided with dots 1031 for scattering light. The light emitted by the LED light source 20 enters the light guide plate 10 from the light entrance surface 101. The light is totally reflected and propagates in the light guide plate 10. When the light propagates to the bottom surface 103, it is scattered by the dots 1031 and finally exits from the light exit surface 102.